Downdraft safety device for combustion gas flues

ABSTRACT

This invention relates to an improvement in a downdraft safety device, e.g., for a gas-heated liquid heater. The device is arranged inside of a cowling provided with lateral outlets, and includes a lower flue gas collecting hood defined in front and in the rear by the front and back panels of the downdraft safety device, and a baffle arranged above the glue gas collecting hood in the vicinity of the outlet connected between front and back panels. The hood defining, inwardly inclined portions of the front and back panels, each provide an opening at their tops for venting the device through the respective front and back panels.

United States Patent [72] Inventors George Hein [56] References Cited Huckeswagen; UNITED STATES PATENTS [2 H Appl No gzlfgg 3,361,127 1/1968 Hein et al. 126/307 A a 221 Filed 0c1.20, 1969 FOREIGN PATENTS [451 Patented Aug. 24,1971 531,032 8/1931 Germany 126/307 A [73] Assignce Joh.Vai1l tKG 634,044 8/1936 Germany 126/307 A [32] Priority Dec. 3, 1968 998,554 7/1965 Great Britain 126/307 A [33] Germany Primary Examiner-Charles J. Myhre [3 H P 18 All0rney- Darbo, Robertson & Vandenburgh ABSTRACT: This invention relates to an improvement in a downdraft safety device, e.g., for a gas-heated liquid heater. The device is arranged inside of a cowling provided with lateral outlets, and includes a lower flue gas collecting hood [S4] FOR defined in front and in the rear by the front and back panels of 2 Claim 2 D the downdraft safety device, and a bafile arranged above the rawmg glue gas collecting hood in the vicinity of the outlet connected [52] U.S. Cl 126/307 A between front and back panels. The hood defining, inwardly [51] Int. Cl F23j 1 1/00 inclined portions of the front and back panels, each provide an [50] Field of Search 126/307, opening at their tops for venting the device through the 307 A respective front and back panels.

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BACKGROUND OF THE INVENTION It is well known that a downdraft safety device of the type indicated is intended, if downdraft occurs, i.e., if wind enters into the flue stack from above, to direct the downdraft, together with uprising flue gases, to lateral outlets of the cowling, and to prevent the downdraft from passing into the combustion chamber. For this purpose, a baffle is provided by which the downdraft is deflected towards lower-lying lateral outlets. If no downdraft is present, the baffle is circumcirculated by the uprising flue gases.

Prior art downdraft safety devices of the type indicated, such as in accordance with the German Pat. Application P 16 79 775.4, fulfil their function for a specific rated output of the apparatus. With the prior constructions, an overload is possible only to a limited extent without endangering the specified burning safety. It is an object of this invention to provide an apparatus of higher output in which the above described principle of the draft diverter is utilized and, for reasons of economy, the same fins are used in the apparatus having a higher output. By way of example, the rated output of a type of ap paratus of previously 79,400 BTU/h can be increased to approximately 95,280 BTU/h. The fin block is increased by the addition of fins. The diameter of the flue pipe being maintained, the flue gas system for the greater flue gas volume in all three states, namely, updraft, obstructed flow, and downdraft, must satisfy the known specifications. By increasing the number of fins, it has already been determined that the apparatus shall be changed only with respect to its width. Therefore, first the flue gas collecting hood following the fin body, of the draft diverter is enlarged. This enlargement renders the lateral exhaust of the flue gas volume more difficult, particularly in the presence of downdraft.

For feeding the greater flue gas volume, a greater height of updraft is required in the apparatus, when the diameter of the flue pipe is maintained, in order to achieve a stronger updraft of the flue gases. To increase this updraft, the height of the upper draft portion-measured from the upper edge of the lateral openings of the draft diverter to the flue pipe-is increased. At the same time, these upper edges are shifted outwardly in keeping with the enlargement of the fin block. Thereby, the great amount of flue gas is trapped in a wider upper portion of the draft diverter and is exhausted by the greater updraft through the flue pipe of same diameter as with an apparatus of less output. The height of the two lateral openings of the draft diverter enters only irrelevantly into this reflection.

To control downdraft from the stack, a baffle plate is used which is known per se. In the enlarged apparatus, this baffle plate is acting to deflect the downdraft towards all sides. The laterally deflected portion of the downdraft volume escapes through the upper portion of the two lateral openings of the downdraft safety device. One portion of the partial downdraft deflected forwardly and backwardly by the baffle plate is divided at the closed front and back panels of the downdraft safety device and joins the two laterally directed flows. The central portion of this downdraft deflected forwardly and backwardly by the baffle plate cannot join the lateral partial flows and evades downwardly.

It is an object of the present invention to provide a downdraft safety device of the type indicated in the beginning, in which the central portion of the downdraft deflected forwardly and backwardly by the baffle plate cannot act in opposition to the uprising flue gas flow from the fin body and impair the combustion.

It is another object of the present invention, with a downdraft safety device of the type indicated in the beginning to render possible an increase of the rated output of the apparatus by the measures hereinbefore described, without impairing the buming safety.

SUMMARY OF THE INVENTION According to the invention these objects are attained by providing one blade-type stamped element open at the top and projecting inwardly in that portion of both the front and back panels, respectively, defining the lower flue gas collecting hood. By these stamped elements, the two residual flows are discharged forwardly and backwardly out of the draft diverter.

DESIGNATION OF THE FIGURES DESCRIPTION OF PREFERRED EMBODIMENT Fin body 1 of a heat exchanger 2 of a gas-heated instantaneous flow heater is followed, at the top, by a downdraft safety device generally referenced 3. Such downdraft safety devices serve the function of ensuring the safe burning of the gas burner (not illustrated) disposed below the heat exchanger 2, under updraft, obstructed flow, and downdraft, in the stack.

The downdraft safety device comprises a flue gas collecting hood 4. This collecting hood is formed by the flat front and back panels 5 and 6 of the downdraft safety device (FIG. 2) as well as by two guide plates 7 and 8 facing each other, inclined over the fin block. After the hot fuel gas has transmitted its heat to the heat exchanger 2, it enters the collecting hood 4. Under updraft, the flue gas then circumcirculates a baffle plate 9 disposed above the collecting hood 4, in order to reunite behind the same. Then, it is exhausted into a stack (not shown) through a flue gas conduit 10 terminating a spaced distance above the baffle plate 9.

When flow in the stack is obstructed, the flue gases discharge into the installation space of the apparatus on both sides through openings 11 and 12 of the downdraft safety device as well as through openings 13 and 14 of cowling l5. Openings l1 and 12 are defined, laterally, by the spaced-apart flat panels 5 and 6 of the downdraft safety device. Openings 11 and 12 are defined below, by a lower end plate 16 closing off the space between the heating body 2 and the cowling l5 and surrounding the fin body 1; openings ll, 12 are defined, at the top, by two panels 17 and 18 inclined towards each other and joining the mouth of flue conduit 10.

Gases flowing downwardly from the flue conduit 10 under downdraft impinge upon the baffle plate 9 from which they are deflected towards all sides. At the same time, the flue gases directed upwardly from flue gas collecting hood 4, from below, impinge upon the underside of the baffle plate 9 and are also deflected towards all sides. By the deflection two main flows are created discharging through openings 11, 13, and 12, 14, respectively.

A portion of the rising flue gas as well as a portion of the downdraft gas impinge upon each other centrally in front of, and behind, baffle plate 9, and are not carried along by the two main flows created. For this reason, one cavitylike, stamped element 19, 20, respectively, is provided in flat front panel 5 and in back panel 6, respectively, each element 19, 20 providing upwardly directed openings 19' and 20, respectively. Openings 19', 20' are about as long as the opening of flue gas collecting hood 4. When stack flow is obstructed, or under downdraft conditions, the previously mentioned central portion of the flue gas flow in front of, and behind, baffle plate 9 are discharged through openings, 19, 20

We claim:

1. In a gas-heated liquid heater downdraft safety device, which device is arranged inside a cowling having lateral cowling outlets, which device includes lateral outlets aligned with said lateral cowling outlets and side panels inwardly of said outlets of the device, which device includes a lower flue gas inlet defined in front and rear by front and back panels, respectively, and said side panels of the downdraft safety device, which device includes a baffle arranged between the flue gas inlet and a flue gas outlet, the baffle being positioned at a level above the tops of the lateral outlets, and at a level substantially below the flue gas outlet from the safety device, the improvement in which:

front and back portions of the flue gas inlet are defined by upwardly and inwardly inclined panels connected at the bottom thereof to the respective front or back panel, said inclined panels forming an inner wall of a conduit connecting the interior of the safety device to the exterior of the safety device. 2. In a downdraft safety device adapted for use in a conduit connecting a combustion chamber to a stack, which device includes a front and back panel, a flue gas inlet at the bottom thereof, a flue gas outlet at the top thereof, baffle means positioned between said inlet and said outlet for preventing direct flow between said inlet and said outlet, said device including relatively large, laterally positioned vents, the top of said vents being at a level below said baffle means, said baffle means permitting flow around all sides thereof, the improvement in which:

the inlet comprises an upwardly and inwardly narrowing hood having a front, back and sidewalls, said front and backwall being stamped from said front and back panel, respectively, each of said front and backwalls providing an opening between the top thereof and the adjacent front or back panel of the device, each of said openings providing communication between the interior and the exterior of the device. 

1. In a gas-heated liquid heater downdraft safety device, which device is arranged inside a cowling having lateral cowling outlets, which device includes lateral outlets aligned with said lateral cowling outlets and side panels inwardly of said outlets of the device, which device includes a lower flue gas inlet defined in front and rear by front and back panels, respectively, and said side panels of the downdraft safety device, which device includes a baffle arranged between the flue gas inlet and a flue gas outlet, the baffle being positioned at a level above the tops of the lateral outlets, and at a level substantially below the flue gas outlet from the safety device, the improvement in which: front and back portions of the flue gas inlet are defined by upwardly and inwardly inclined panels connected at the bottom thereof to the respective front or back panel, said inclined panels forming an inner wall of a conduit connecting the interior of the safety device to the exterior of the safety device.
 2. In a downdraft safety device adapted for use in a conduit connecting a combustion chamber to a stack, which device includes a front and back panel, a flue gas inlet at the bottom thereof, a flue gas outlet at the top thereof, baffle means positioned between said inlet and said outlet for preventing direct flow between said inlet and said outlet, said device including relatively large, laterally positioned vents, the top of said vents being at a level below said baffle means, said baffle means permitting flow around all sides thereof, the improvement in which: the inlet comprises an upwardly and inwardly narrowing hood having a front, back and sidewalls, said front and backwall being stamped from said front and back panel, respectively, each of said front and backwalls providing an opening between the top thereof and the adjacent front or back panel of the device, each of said openings providing communication between the interior and the exterior of the device. 